Various automatic transmissions with several gears that can be engaged without range-change are known. For example, DE 199 12 480 A1 describes an automatic transmission of this type with three single-web planetary gearwheel assemblies and three brakes and two clutches for the engagement of six forward gears and one reverse gear, which is characterized by transmission ratios which are very appropriate for motor vehicles, with a high overall spread and suitable gear progressions and a high starting ratio in the forward direction. The individual gears are engaged by the selective closing in each case of two of the six shift control elements, so that to shift from one gear to the next gear up or down, in each case only one of the shift control elements currently actuated is opened and another shift control element is closed.
In this case a drive input shaft of the automatic transmission is permanently connected with a sun gearwheel of the second planetary gearwheel assembly. Furthermore, the drive input shaft can be connected via the first clutch to a sun gearwheel of the first planetary gearwheel assembly and/or via the second clutch to a web of the first planetary gearwheel assembly. In addition or alternatively, the sun wheel of the first planetary gearwheel assembly can be connected via the first brake to a housing of the automatic transmission and/or the web of the first planetary gearwheel assembly via the second brake to the housing and/or a sun gearwheel of the third planetary gearwheel assembly via the third brake to the housing.
For the kinematic clutch of the individual planetary gearwheel assemblies to one another, DE 199 12 480 A1 discloses two different versions. In the first version it is provided that a drive output shaft of the automatic transmission is permanently connected with a web of the third planetary gearwheel assembly and an annular gearwheel of the first planetary gearwheel assembly, and that the web of the first planetary gearwheel assembly is permanently connected with an annular gearwheel of the second planetary gearwheel assembly and a web of the second planetary gearwheel assembly is permanently connected with an annular gearwheel of the third planetary gearwheel assembly. The drive input and output shafts in this case can either be arranged coaxially with one another on opposite sides of the transmission housing, or axis-parallel to one another on the same side thereof. In the second version it is provided that the drive output shaft is connected permanently with the web of the second planetary gearwheel assembly and the annular gearwheel of the first planetary gearwheel assembly, the web of the first planetary gearwheel assembly is connected permanently with the annular gearwheel of the third planetary gearwheel assembly and the annular gearwheel of the second planetary gearwheel assembly is connected permanently with the web of the third planetary gearwheel assembly. Such a structure is particularly suitable for a coaxial arrangement of the drive input and output shafts.
In relation to the spatial arrangement of the planetary gearwheel assemblies, DE 199 12 480 A1 proposes to arrange the three planetary gearwheel assemblies coaxially in series next to one another, with the second planetary gearwheel assembly axially between the first and third planetary gearwheel assemblies. As regards the spatial arrangement of the individual shift control elements relative to one another and relative to the planetary gearwheel assemblies, DE 199 12 480 A1 proposes always to arrange the first and second brakes next to one another, such that the second brake is always directly axially adjacent to the first planetary gearwheel assembly, and the third brake always on the side of the third planetary gearwheel assembly facing away from the first planetary gearwheel assembly, and the two clutches are always directly next to one another. In a first arrangement variant both clutches are arranged on the side of the first planetary gearwheel assembly facing away from the third planetary gearwheel assembly, with the first clutch directly axially adjacent to the first brake and closer to the first planetary gearwheel assembly than the second clutch. In combination with a non-coaxial position of the drive input and output shafts, in a second arrangement variant it is proposed that both clutches are arranged on the side of the third planetary gearwheel assembly facing away from the first planetary gearwheel assembly, with the second clutch closer to the third planetary gearwheel assembly than the first clutch and axially adjacent to a drive output spur gearwheel which is in active connection with the output shaft, this in turn being arranged on the side of the third brake facing away from the third planetary gearwheel assembly.
The purpose of the present invention is to provide component arrangements alternative to those of the automatic transmission known from the prior art of DE 199 12 480 A1, with the most compact possible transmission structure. Preferably, the automatic transmission should be able to be used in a motor vehicle with drive input and output shafts not arranged coaxially with one another, but, with comparatively simple modifications, possibly also when the input and output shafts are coaxial.
According to the invention this objective is achieved by a multi-stage automatic transmission having the characteristics of claim 1. Advantageous features and further developments of the invention emerge from the subordinate claims.